20157779 has 2 divisors, whose sum is σ = 20157780. Its totient is φ = 20157778.

The previous prime is 20157751. The next prime is 20157791. The reversal of 20157779 is 97775102.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20157779 is a prime.

It is not a weakly prime, because it can be changed into another prime (20157749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10078889 + 10078890.

It is an arithmetic number, because the mean of its divisors is an integer number (10078890).

Almost surely, 2^20157779 is an apocalyptic number.

20157779 is a deficient number, since it is larger than the sum of its proper divisors (1).

20157779 is an equidigital number, since it uses as much as digits as its factorization.

20157779 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30870, while the sum is 38.

The square root of 20157779 is about 4489.7415293088. The cubic root of 20157779 is about 272.1536896358.

The spelling of 20157779 in words is "twenty million, one hundred fifty-seven thousand, seven hundred seventy-nine".